As the HIV research and patient communities place greater emphasis on cure strategies, there is an urgent need to understand HIV rebound and predict its kinetics. Previous trials have demonstrated that a significant majority of individuals rebound within one year of ART interruption (>85%, depending on time of therapy initiation), resulting in high viral loads and loss of CD4+ T cells.[REF SMART] Current research is focused on understanding the critical factors driving rebound, which should allow prediction of rebound kinetics in individual patients, and may suggest strategies to delay or prevent rebound. The proposed RETIRE-HIV Program will provide a framework for study of host immunologic factors that impact upon rebound in observational and interventional trials, in humans and non-human primates. The Biostatistics Core is integral to this cooperative effort, providing a coordinated, rigorous approach to the diverse datasets that will be gathered. These include results from a retrospective study of well-characterized human patients undergoing rebound (Project 1, Aim 2), a prospective cohort to be followed throughout therapeutic immunization and rebound (Project 1, Aim 3), a non-human primate study of the effects of therapeutic vaccination with a unique candidate eliciting Mamu-E-restricted responses (Project 2, Aim 2), and a non- human primate study of the effects of wild-type RhCMV infection on natural elicitation of Mamu-E-restricted responses (Project 3, Aim 3). The comprehensive and integrated biostatistical studies undertaken by this Core will ensure that a rigorous and sophisticated analysis is undertaken of each study and that results from these various experiments influence the conduct of others. Overall, the mission of the Biostatistics Core is to facilitate performance of rigorous research in each project and to provide an integrated analysis of gathered data. The functions of this core include study design, protocol and proposal development, management of research-related data management systems, data analysis and interpretation of findings, and publication of results. The specific aims are: 1. To assist in study design and analysis planning, including power analysis/sample size calculations. 2. To develop and maintain study databases. 3. To provide epidemiological, biostatistical, and data analysis expertise.